U.S. Pat. No. 5,110,226 discloses an electrically driven air pump whose operation is accompanied by vibrations of variable magnitude due to imbalance of the impeller on wheel and the electric motor as well as to the magnetic rotating field which is produced. These vibrations are transported to the pump support or to the apparatus to which it is connected and produces a high frequency operating noise.
DE-A1 41 07 049 discloses an electrically driven air pump which includes means for reducing the vibration and operating noise. Principally, such means comprises two elastomer rings between the electric motor and the housing for support of the motor. The rings are arranged between the electric motor and the housing in a particular fashion in which the second ring is supported by the housing through a spring acting under tension between a cover and the elastomer ring.
Although the above measures lead to a reduction in the vibration and operating noise of the electrically driven air pump, it involves considerable cost for the manufacture of the structural parts. In addition, the various sealed joints may become unsealed due to the multiplicity of structural parts which are connected by screws whereby the efficiency of the pump is reduced.